Aerogel modified polypropylene, ultra-light heat-insulating melt-blown non-woven fabric and preparation method thereof
Technical Field
The invention relates to the field of non-woven fabric materials, in particular to aerogel modified polypropylene, ultra-light heat-insulation melt-blown non-woven fabric and a preparation method thereof.
Background
The non-woven fabric is a fabric formed without spinning woven fabric, and is formed by simply forming a fiber web structure by orienting or randomly arranging textile short fibers or filaments and then reinforcing the fiber web structure by adopting a mechanical method, a thermal bonding method or a chemical method.
At present, the process for preparing nonwoven fabrics is also diversified, for example, in the article of treatise on the preparation and performance research of silica aerogel/polypropylene melt-blown nonwoven materials, the preparation of aerogel modified polypropylene by melt blending polypropylene and aerogel is givenA method of melt blowing a nonwoven fabric. In CN104446333B, PP (polypropylene) fiber is silanized by APTES (3-aminopropyltriethoxysilane), dipped in TEOS solution, and co-hydrolyzed and co-crosslinked gel reacted to produce fiber with SiO2The non-woven fabric of the aerogel thin layer is subjected to multiple times of cross impregnation, cohydrolysis and co-crosslinking gel reaction, and is dried to obtain the PP fiber reinforced SiO2A gel material. CN 106838547 a discloses a non-dusting thermal insulation felt (board) containing nanoporous thermal insulation material and a preparation method thereof, wherein the technique adopts the conventional needle punching technique or cotton carding technique to make fibers into a fiber base material of a sheet-shaped or roll-shaped felt, then a binder is dipped or sprayed on the fiber surface of the base material, and finally the ground nanoporous thermal insulation material is sprayed on the fibers to obtain the thermal insulation felt (board) bonded with the nanoporous material.
However, the above methods all have certain technical problems, such as: in the thesis of silica aerogel/polypropylene melt-blown nonwoven material preparation and performance research, a melt blending method is used for preparing aerogel modified PP melt-blown nonwoven fabric, and due to the great difference of bulk densities of PP and aerogel, the nonwoven fabric with uniform aerogel dispersion and adjustable particle size is difficult to obtain in melt-blown equipment with limited melting range. CN104446333B needs to carry out surface silanization treatment on PP fiber, then is soaked in TEOS solution for many times, and carries out cohydrolysis and co-crosslinking gel reaction, so that the process is complicated, the consumed time is long, and the PP fiber needs to be chemically modified, so that the mechanical property of the PP fiber is easily reduced, and the mechanical property of a final finished product is reduced; in addition, SiO which is not in direct contact with the surface of the PP fiber2The xerogel is easy to fall off in the using process, the service life of the material is reduced, the using environment is deteriorated, and the health of a user is harmed. In CN 106838547A, a method of compounding a fiber layer, a bonding layer and a nano-pore heat insulation layer is used for preparing a dust-free heat insulation felt (board), the process is complicated, and the content of the nano-pore heat insulation material in the heat insulation felt (board) and the depth of the nano-pore heat insulation material entering a fiber matrix are greatly influenced by the size of pores among fibers in the fiber matrix; in addition, the technology adopts a spraying method to add nano-pore heat-insulating material and fibers in the nano-pore heat-insulating materialThe dimensional matrix is equivalent to a filter material, the nano-pore heat insulation material is easily blocked on the outer surface layer of the matrix, the effect of uniform dispersion of the nano-pore heat insulation material is difficult to achieve, and foreign matters such as dust and the like are easily bonded on the bonding layer on the heat insulation felt (plate) in the using process, so that the appearance, the air permeability and other performances of the heat insulation felt (plate) are influenced.
Disclosure of Invention
The invention aims to provide aerogel modified polypropylene, ultra-light heat-insulating melt-blown non-woven fabric and a preparation method thereof, and aims to solve the technical problems of poor dispersion uniformity and uncontrollable particle size of aerogel in the prior art of preparing the aerogel modified non-woven fabric by a melt-blowing method.
In order to achieve the above objects, according to one aspect of the present invention, there is provided a method for preparing aerogel-modified polypropylene. The preparation method comprises the following steps: before or during the polymerization reaction, adding aerogel and a reaction material with lower viscosity for blending to realize uniform dispersion of the aerogel, and preparing aerogel modified polypropylene by a propylene polymerization process; the reaction material comprises a propylene monomer, a catalyst and an auxiliary agent, the granularity of the aerogel is between 20nm and 100 mu m, the porosity is between 40 and 99.9 percent, the bulk density is 3 to 500g/L, and the volume fraction accounts for 20 to 60 percent of the volume of the ultralight heat-insulating melt-blown non-woven fabric prepared from the aerogel modified polypropylene.
Further, the propylene polymerization process is a gas-phase propylene polymerization process, a slurry propylene polymerization process or a liquid-phase propylene polymerization process.
Further, in the gas phase propylene polymerization process, adding aerogel and a reaction material with lower viscosity to blend comprises blending aerogel and propylene monomer, or blending with a catalyst, or adding the aerogel and the propylene monomer into a polymerization reaction device separately to blend with the reaction material, or any combination of the above blending modes.
Further, in the slurry propylene polymerization process, the adding of the aerogel and the reaction material with lower viscosity to blend comprises blending the aerogel and slurry formed by the catalyst and the hydrocarbon solvent, or blending with the propylene monomer, or adding the aerogel into the polymerization reaction device independently to blend with the reaction material, or any combination of the above blending modes.
Further, the slurry propylene polymerization process further comprises: the obtained polypropylene raw material is subjected to deashing, settling separation of the solvent and the random material, and kneading.
Further, in the liquid phase propylene polymerization process, adding aerogel and a reaction material with a lower viscosity to blend comprises blending aerogel and a propylene monomer, or blending with a catalyst, or adding the aerogel and the propylene monomer into a polymerization reaction device separately to blend with the reaction material, or combining the above blending modes at will.
Further, the liquid phase propylene polymerization process includes flash separation to remove the random copolymer.
According to another aspect of the invention, a preparation method of the ultralight heat-insulating melt-blown non-woven fabric is provided. The preparation method comprises the following steps: preparing aerogel modified polypropylene by any one of the methods; and (3) the aerogel modified polypropylene enters a melt-blowing device to prepare the ultralight heat-insulating melt-blowing non-woven fabric.
According to another aspect of the present invention, there is provided an aerogel modified polypropylene, which is prepared by any one of the above methods for preparing an aerogel modified polypropylene, wherein the size of the aerogel in the aerogel modified polypropylene is 15nm to 100 μm.
According to another aspect of the invention, the ultralight heat-insulating melt-blown non-woven fabric is prepared by the preparation method of the ultralight heat-insulating melt-blown non-woven fabric, wherein the size of aerogel in the ultralight heat-insulating melt-blown non-woven fabric is 15 nm-10 microns.
By applying the technical scheme of the invention, aerogel modified polypropylene particles with good melt-blown performance and melt-blown polypropylene non-woven fabric with ultra-light heat insulation and heat preservation functions, in which aerogel is uniformly dispersed, are prepared by selecting aerogel with different particle sizes and porosities, changing the addition amount of the aerogel and improving the blending mode without adding any dispersing auxiliary agent, and the aerogel in the non-woven fabric does not fall off in the using process and has long service life.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.
In order to solve the problems of poor dispersion uniformity, uncontrollable granularity and the like of aerogel in the preparation of aerogel modified non-woven fabric by a melt-blown method in the prior art, based on an in-situ polymerization method, the invention provides a method for preparing modified polypropylene with controllable statistical size, uniform dispersion and good melt-blown performance by using a propylene monomer as a raw material and limiting specific aerogel characteristic parameters (granularity, porosity, packing density (3-500 g/L) ((packing density: mass per unit volume under a natural packing state, including mass per unit volume inside and outside pores and gaps among particles), aerogel addition amount and a blending mode, and the like, and the aerogel modified melt-blown PP (polypropylene) non-woven fabric with good heat insulation and heat preservation functions can be obtained by melt-blowing. The invention can also effectively avoid the problems of easy shedding of aerogel, short service life, deterioration of use environment, harm to the body health of a user and the like in the prior art of preparing the aerogel felt (board) by a fiber filling method.
According to an exemplary embodiment of the present invention, a method for preparing aerogel-modified polypropylene is provided. The preparation method comprises the following steps: before or during the polymerization reaction, adding aerogel and a reaction material with lower viscosity for blending to realize uniform dispersion of the aerogel, and preparing aerogel modified polypropylene by a propylene polymerization process; the reaction material comprises a propylene monomer, a catalyst and an auxiliary agent, the granularity of the aerogel is between 20nm and 100 mu m, the porosity is between 40 and 99.9 percent, the bulk density is 3 to 500g/L, and the volume fraction accounts for 20 to 60 percent of the volume of the ultralight heat-insulating melt-blown non-woven fabric prepared from the aerogel modified polypropylene.
The catalyst can be a Ziegler-Natta catalyst system or a metallocene catalyst system, the dosage is 30-0.8 kg.pp/g.cat (0.1-5 ppm), and the auxiliary agent can be hydrogen, and the dosage is 50-1000 ppm.
By applying the technical scheme of the invention, aerogel modified polypropylene particles with good melt-blown performance and aerogel uniformly dispersed and melt-blown polypropylene non-woven fabric with ultra-light heat insulation and heat preservation functions are prepared by selecting aerogels with different particle sizes and porosities, changing the addition amount of the aerogel and improving the blending mode under the condition of not adding any dispersing auxiliary agent, and in addition, the aerogel modified polypropylene is obtained by using an in-situ polymerization method, so that the polymer with uniformly dispersed powder and adjustable particle size can be obtained by the preparation method, and the polymer has a sea-island structure (the polypropylene is 'sea' and the small aerogel particles are 'islands'), thereby ensuring that the aerogel in the non-woven fabric does not fall off in the use process and has long service life.
According to a typical embodiment of the present invention, the propylene polymerization process is a gas phase propylene polymerization process, a slurry propylene polymerization process or a liquid phase propylene polymerization process.
According to a typical embodiment of the present invention, the adding of the aerogel to the reaction material having a lower viscosity to blend in the gas phase propylene polymerization process comprises blending the aerogel with a propylene monomer, or with a catalyst, or adding the aerogel to a polymerization reaction device separately to blend with the reaction material, or any combination thereof.
According to a typical embodiment of the present invention, the adding of the aerogel and the blending of the reaction material having a relatively low viscosity in the slurry propylene polymerization process comprises blending the aerogel with a slurry of the catalyst and the hydrocarbon solvent, or with the propylene monomer, or separately adding the aerogel to the polymerization reaction device to blend with the reaction material, or any combination thereof.
Preferably, the slurry propylene polymerization process further comprises: the obtained polypropylene raw material is subjected to deashing, settling separation of the solvent and the random material, and kneading.
According to a typical embodiment of the present invention, the adding of the aerogel to the reaction material with a lower viscosity to blend in the liquid phase propylene polymerization process comprises blending the aerogel with a propylene monomer, or blending with a catalyst, or adding the aerogel to a polymerization reaction device separately to blend with the reaction material, or any combination thereof.
Preferably, the liquid phase propylene polymerization process includes flash separation to remove the random copolymer.
According to an exemplary embodiment of the present invention, a method for preparing an ultra-light heat-insulating melt-blown nonwoven fabric is provided. The preparation method comprises the following steps: preparing aerogel modified polypropylene by any one of the methods; and (3) the aerogel modified polypropylene enters a melt-blowing device to prepare the ultralight heat-insulating melt-blowing non-woven fabric.
According to an exemplary embodiment of the present invention, an aerogel-modified polypropylene is provided. The aerogel modified polypropylene is prepared by any one of the preparation methods, and the size of aerogel in the aerogel modified polypropylene is 15 nm-100 mu m.
According to an exemplary embodiment of the present invention, an ultra-light thermal insulation meltblown nonwoven fabric is provided. The ultralight heat-insulating melt-blown non-woven fabric is prepared by the preparation method, wherein the size of aerogel in the ultralight heat-insulating melt-blown non-woven fabric is 15 nm-10 mu m. The non-woven fabric has the advantages of light weight, good heat preservation effect and the like.
The beneficial effects of the present invention will be further illustrated by the following examples, and the steps or materials not described in detail in the following examples can be implemented by means of conventional techniques or conventional materials in the art.
Example 1
Gas phase method:
dehydrating and drying the aerogel by a heating drying or dehydrating agent method; and deoxidizing the dehydrated aerogel by using inert gas or deoxidizing agent to obtain the dried and deoxidized aerogel.
The catalyst is ultra-high activity TiCl3Diisobutyldimethoxysilane/MgCl2/Et3Al (mass ratio of 25:55:21:53, TiCl)38ppm), refined propylene monomer, hydrogen (150ppm) and dehydrated deoxidized aerogel (2 wt% of propylene) were sequentially added into the first horizontal stirred bed to reactThe vessel was started and stirred, and the temperature was raised to 71 ℃ under a pressure of 2.25 MPa. And conveying the obtained polypropylene powder into a second horizontal stirred bed reactor through a powder conveying fan, simultaneously adding refined propylene monomers and hydrogen into the second horizontal stirred bed reactor, starting stirring, heating to 71 ℃, and keeping the pressure at 2.25 MPa. After the polymerization reaction, the powder is separated from the gas in a bag filter, dried and deactivated in a degassing bin, and then enters an extrusion granulation system for mixing and granulation.
The polypropylene is tested according to GB/T30923-.
Carrying out melt-blowing on the polypropylene particles under the conditions of conventional polypropylene melt-blowing equipment and process parameters to obtain the melt-blown polypropylene non-woven fabric containing aerogel, wherein the heat conductivity coefficient of the melt-blown polypropylene non-woven fabric is 0.029W/(m.K), the volume fraction of the aerogel accounting for the final ultra-light heat-insulation heat-preservation melt-blown non-woven fabric is 56%, and the specific melt-blown parameters are as follows: the die head temperature is 245 ℃, the distance between the die head and the catcher is 0.152m, the hot air temperature is 145 ℃, and the hot air speed is 500 m/s.
Example 2
Liquid phase method:
the aerogel was subjected to dry deoxygenation pretreatment as in example 1.
At 12m3Adding 3000kg of refined propylene monomer into a polymerization kettle, adding dehydrated and deoxidized aerogel into the polymerization kettle from a feed inlet, starting stirring, and adding a catalyst TiCl3/AlEt2Cl/Lewis base (TiCl)350ppm, Al/Ti molar ratio of 11, Lewis base/Ti molar ratio of 3, and hydrogen (150ppm), and polymerization was started by heating to 75 ℃ and a pressure of 3.5 MPa. And stopping the reaction when the polymerization reaction reaches 70-80 percent of conversion rate, discharging unreacted propylene monomers, discharging the polypropylene to a flash evaporation kettle, introducing air after flash evaporation, discharging to obtain polypropylene powder, and extruding and granulating to obtain polypropylene particles.
The polypropylene is tested according to GB/T30923-.
Carrying out melt-blowing on the polypropylene particles under the conditions of conventional polypropylene melt-blowing equipment and process parameters to obtain the melt-blown polypropylene non-woven fabric containing aerogel, wherein the heat conductivity coefficient of the melt-blown polypropylene non-woven fabric is 0.031W/(m.K), the volume fraction of the aerogel accounting for the final ultra-light heat-insulation heat-preservation melt-blown non-woven fabric is 49%, and the specific melt-blown parameters are as follows: the die head temperature is 240 ℃, the distance between the die head and the catcher is 0.152m, the hot air temperature is 140 ℃, and the hot air speed is 400 m/s.
Example 3
Slurry method:
the aerogel was subjected to dry deoxygenation pretreatment as in example 1.
Catalyst TiCl3/AlEt2Cl/Lewis base (TiCl)350ppm, the molar ratio of aluminum to titanium is 11, the molar ratio of Lewis base to titanium is 3) and hydrogen (150ppm) are added into a prepolymerization reactor and mixed with an inert solvent hexane to form a slurry, and a certain amount of gaseous refined propylene is added under a nitrogen seal to polymerize at the temperature of 10-25 ℃ for 1-2 h to obtain the prepolymerized catalyst.
Adding the prepolymerized catalyst and the dehydrated and deoxidized aerogel into liquid refined propylene, starting stirring, heating to 70 ℃, and starting polymerization under the pressure of 1.0 MPa. And stopping the reaction when the polymerization reaction reaches 70-80 percent of conversion rate, discharging unreacted propylene monomers, discharging the polypropylene to a flash evaporation kettle, introducing air after flash evaporation, washing, centrifugally separating, drying, discharging to obtain polypropylene powder, and extruding and granulating to obtain polypropylene particles.
The polypropylene is tested according to GB/T30923-.
Carrying out melt-blowing on the polypropylene particles under the conditions of conventional polypropylene melt-blowing equipment and process parameters to obtain the melt-blown polypropylene non-woven fabric containing aerogel, wherein the heat conductivity coefficient of the melt-blown polypropylene non-woven fabric is 0.035W/(m.K), the aerogel accounts for 40% of the volume fraction of the final ultra-light heat-insulating heat-preserving melt-blown non-woven fabric, and the specific melt-blown parameters are as follows: the die head temperature is 240 ℃, the distance between the die head and the catcher is 0.152m, the hot air temperature is 140 ℃, and the hot air speed is 400 m/s.
Example 4
Slurry method:
the aerogel was subjected to dry deoxygenation pretreatment as in example 1.
Dehydrating and deoxidizing the aerogel and a catalyst TiCl3/AlEt2Cl/Lewis base (TiCl)350ppm, the molar ratio of aluminum to titanium is 11, the molar ratio of Lewis base to titanium is 3) and hydrogen (150ppm) are added into a prepolymerization reactor and mixed with an inert solvent hexane to form a slurry, and a certain amount of gaseous refined propylene is added under a nitrogen seal to polymerize at the temperature of 10-25 ℃ for 1-2 h to obtain the prepolymerized catalyst.
Adding the catalyst into liquid refined propylene, starting stirring, heating to 70 ℃, and starting polymerization under the pressure of 1.0 MPa. And stopping the reaction when the polymerization reaction reaches 70-80 percent of conversion rate, discharging unreacted propylene monomers, discharging the polypropylene to a flash evaporation kettle, introducing air after flash evaporation, washing, centrifugally separating, drying, discharging to obtain polypropylene powder, and extruding and granulating to obtain polypropylene particles.
The polypropylene is tested according to GB/T30923-.
Carrying out melt-blowing on the polypropylene particles under the conditions of conventional polypropylene melt-blowing equipment and process parameters to obtain the melt-blown polypropylene non-woven fabric containing aerogel, wherein the thermal conductivity coefficient of the melt-blown polypropylene non-woven fabric is 0.030W/(m.K), the aerogel accounts for 52% of the volume fraction of the final ultra-light heat-insulating heat-preserving melt-blown non-woven fabric, and the melt-blown parameters are as follows: the die head temperature is 245 ℃, the distance between the die head and the catcher is 0.152m, the hot air temperature is 145 ℃, and the hot air speed is 500 m/s.
Example 5:
gas phase method:
dehydrating and drying the aerogel by a heating drying or dehydrating agent method; and deoxidizing the dehydrated aerogel by using inert gas or deoxidizing agent to obtain the dried and deoxidized aerogel.
The catalyst is ultra-high activity TiCl3Diisobutyldimethoxysilane/MgCl2/Et3Al (mass ratio of 25:55:21:53, TiCl)38ppm), refined propylene monomer and hydrogen (150ppm) were sequentially added to the first horizontal stirred bed reactor, the stirring was started, the temperature was raised to 71 ℃ and the pressure was 2.25 MPa. The resulting polypropyleneAnd (3) conveying the olefin powder into a second horizontal type stirred bed reactor through a powder conveying fan, simultaneously adding dehydrated and deoxidized aerogel (0.8 wt% of propylene in the first horizontal type stirred bed reactor), refined propylene monomer and hydrogen into the second horizontal type stirred bed reactor, starting stirring, heating to 71 ℃, and keeping the pressure at 2.25 MPa. After the polymerization reaction, the powder is separated from the gas in a bag filter, dried and deactivated in a degassing bin, and then enters an extrusion granulation system for mixing and granulation.
The polypropylene is tested according to GB/T30923-.
Carrying out melt-blowing on the polypropylene particles under the conditions of conventional polypropylene melt-blowing equipment and process parameters to obtain the melt-blown polypropylene non-woven fabric containing aerogel, wherein the heat conductivity coefficient of the melt-blown polypropylene non-woven fabric is 0.058W/(m.K), the volume fraction of the aerogel accounting for the final ultra-light heat-insulation heat-preservation melt-blown non-woven fabric is 23%, and the specific melt-blown parameters are as follows: the die head temperature is 245 ℃, the distance between the die head and the catcher is 0.152m, the hot air temperature is 145 ℃, and the hot air speed is 500 m/s.
Comparative example 1:
slurry method:
the aerogel was subjected to dry deoxygenation pretreatment as in example 1.
Catalyst TiCl3/AlEt2Cl/Lewis base (TiCl)350ppm, the molar ratio of aluminum to titanium is 11, the molar ratio of Lewis base to titanium is 3) and hydrogen (150ppm) are added into a prepolymerization reactor and mixed with an inert solvent hexane to form a slurry, and a certain amount of gaseous refined propylene is added under a nitrogen seal to polymerize at the temperature of 10-25 ℃ for 1-2 h to obtain the prepolymerized catalyst.
Adding the prepolymerized catalyst and the dehydrated and deoxidized aerogel into liquid refined propylene, starting stirring, heating to 70 ℃, and starting polymerization under the pressure of 1.0 MPa. And stopping the reaction when the polymerization reaction reaches 70-80 percent of conversion rate, discharging unreacted propylene monomers, discharging the polypropylene to a flash evaporation kettle, introducing air after flash evaporation, washing, centrifugally separating, drying, discharging to obtain polypropylene powder, and extruding and granulating to obtain polypropylene particles.
The polypropylene is tested according to GB/T30923-.
Carrying out melt-blowing on the polypropylene particles under the conditions of conventional polypropylene melt-blowing equipment and process parameters to obtain the melt-blown polypropylene non-woven fabric containing aerogel, wherein the heat conductivity coefficient of the melt-blown polypropylene non-woven fabric is 0.084W/(m.K), the volume fraction of the aerogel accounting for the final ultra-light heat-insulation heat-preservation melt-blown non-woven fabric is 10%, and the specific melt-blown parameters are as follows: the die head temperature is 240 ℃, the distance between the die head and the catcher is 0.152m, the hot air temperature is 140 ℃, and the hot air speed is 400 m/s.
From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects:
1) the method provides a simple, convenient and efficient aerogel blending mode, and obtains aerogel modified PP with good melt-blown performance and the ultra-light heat-insulating PP melt-blown non-woven fabric;
2) realize the regulation and control of the particle size and the dispersity of aerogel in the polypropylene and the melt-blown non-woven fabric thereof.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.